OICC Press International Nano Letters 2228-5326 12 3 (September 2022) 2022 06 04 The effects of molar ratio and calcination temperature on NiO nanoparticles’ properties 10.1007/s40089-022-00371-3 EN Fatemeh Mashayekhi Department of Physics, Safadasht Branch, Islamic Azad University, Tehran, IR Journal Article 2022 06 04 Abstract Nickel oxide nanoparticles (NiO NPs) embedded in SiO 2 matrix were prepared by the precipitation method. The different sizes of NiO NPs were achieved at various calcination temperatures (600–1000 °C) and different molar ratios of Ni/Si (1, 1.05, 1.15 and 1.24). The SEM images show the morphology and uniform distribution of NiO NPs in the prepared samples. The size, spherical shapes and good dispersion of NiO NPs in the SiO 2 matrix are illustrated by TEM images. The dark spots and gray background indicated the NiO NPs and the SiO 2 matrix, respectively. The crystalline structures of samples and the approximate crystalline size of the nanoparticles were achieved by XRD patterns. The paramagnetic property of the prepared sample was investigated by a vibration sample magnetometer. In this study, the observed size of the nanoparticles increased by increasing the calcination temperatures and molar ratio of Ni/Si and also SiO 2 is a suitable matrix for the synthesis of small nanoparticles. Thus, this method is an appropriate method for fabricating NiO NPs.